Added documentation.

README.md

@@ -15,6 +15,7 @@ information in configurable prompt segments.
     * branch / tag name
     * current action status (rebasing, merging, etc.,)
     * being behind / ahead of your remote by some number of commits
+    * number of stashes (git only)
     * conditionally shows remote tracking branch if the name differs from local
     * various working tree statuses (e.g., unstaged, staged, etc.,)
 * Shows return-code of the last command if it is an error code
@@ -119,6 +120,17 @@ Example:
     # just show the 6 first characters of changeset
     POWERLEVEL9K_CHANGESET_HASH_LENGTH=6
 
+##### Symbols
+
+The `vcs` segment uses various symbols to tell you the state of your repository:
+
+* `↑4` - The number of commits your repository is ahead of your remote branch
+* `↓5` - The number of commits your repository is behind of your remote branch
+* `⍟3` - The number of stashes, here 3.
+* `●`  - There are unstaged changes in your working copy
+* `✚`  - There are staged changes in your working copy
+* `?`  - There are files in your working copy, that are unknown to your repository
+
 ### Styling
 
 You can configure the look and feel of your prompt easily with some built-in